1. Technical Field
The present invention relates to a method and apparatus for confirming whether a correct connection condition is attained or not in a terminal connecting portion in which male terminals are inserted respectively into female terminals to make an electrical connection therebetween.
2. Related Art
The conventional art will be described with taking as an example a terminal connecting portion of a junction block serving as an electric junction box in which an electronic control unit used in an automobile is connected to a power source line, a grounding line, switch signal lines, motor signal lines, and the like.
As shown in FIG. 11, a junction block A is configured by housing a bus bar plate 4 formed by resin-molding a plurality of bus bars 3, between lower and upper cases 1 and 2. A printed circuit board 5 of an electronic control unit is mounted on the upper case 2 of the junction block A, and then covered by a lid 6.
Male terminals (tab terminals) 7 are disposed on the bus bars 3 with being directed upward. The male terminals 7 are passed through the printed circuit board 5, and then inserted respectively into female terminals (not shown in the figure) of a connector 8 which is disposed on the board 5. As a result, the male and female terminals are connected to each other so as to make electrical connections between the bus bars 3 and the printed circuit board 5.
FIGS. 12 and 13 show a structure for connecting the male terminals 7 of the bus bars 3 with the female terminals 9 of the connector 8.
Each of the female terminals 9 is formed into a rectangular tubular shape by an electrically conductive thin metal plate, and disposed in a space defined by a connector base 10 and a connector cover 11. The reference numeral 9a denotes an elastic contact piece of the female terminal 19, and 9b denotes a connect piece which is connected by soldering to a wiring 12 of the printed circuit board 5.
Each of the male terminals 7 is passed through holes 13 and 14 of the printed circuit board 5 and the connector base 10 to be inserted into the corresponding one of the female terminals 9, and then caused to be in elastic contact with the elastic contact piece 9a by the spring force of the piece so as to be electrically connected to the female terminal 9.
[Problems to be Solved]
In such a terminal connecting structure, a connection error such as that the male terminal 7 is erroneously inserted into one of the female terminals 9 which is deviated by one terminal position from the correct female terminal, or that the insertion depth is insufficient may be caused because of the following reasons:
(1) the male and female terminals 7 and 9 are not always in correspondence relationships (the male terminals 7 are sometimes smaller in number than the female terminals); and
(2) the fitting condition of the terminals 7 and 9 cannot be sometimes visually confirmed.
Conventionally, a method of checking whether a correct connection condition is attained or not is therefore performed by experimentally operating the electronic control unit so as to actually activate functions. This functional test causes the conforming work to be cumbersome.
Even when the connection condition is incorrect, the incorrect condition is not always detected as a malfunction, and hence the confirmation is inaccurately performed, so that the reliability is lowered. In consideration of this, visual confirmation or the like is performed as far as possible, or the connecting work must be carefully conducted with attention. Therefore, the efficiency of the connecting work is lowered.